Its excellent photoelectric property due to special structure causes extensive attention since the discovery of quantum dot. One of most prominent performance of quantum dot is “fluorescence property”, which has performances of narrower peak width at half height, small particle, no scattering loss and adjustable spectrum with the size. However, the size of most quantum dot is 3-10 nanometers, surface area is very big, and quantum dot is easy to react with oxygen and water in air in use procedure, and multiple defects are formed on the surface, resulting in quenching fluorescence, and poor stability limits the use of quantum dot greatly.
At present stage, there are mainly two kinds of methods to improve stability of quantum dot: (1) preparing core-shell structure quantum dot to improve stability of quantum dot, however, the effect is limited only by adding thickness of shell layer. (2) improving stability of quantum dot by methods of silicon dioxide coating or macromolecule coating, however, these methods all have deficiencies, in coating process, the surface of quantum dot is damaged to reduce fluorescence efficiency of quantum dot. Therefore, it is an urgent problem to improve stability of quantum dot.
Chinese patent CN 103058274A discloses a preparation method of metal-doped titanium oxide quantum dots, and especially relates to a method for preparing metal-doped titanium oxide quantum dots by using high-temperature oil phase. The invention belongs to the technical field of quantum dots. The method comprises the steps that: (1) a metal titanium compound A and a doping metal compound B are dissolved in a solvent C, such that a solution D is formed; (2) a ligand E is added into the solution D, such that a solution F is formed; (3) the solution F is vacuumed and is charged with nitrogen; a temperature is increased to a required value, and stirring is carried out for a required period of time; the solution is cooled to room temperature; and the vacuuming and nitrogen charging process can be repeated if needed; and (4) the solution F obtained in the step (3) is subjected to centrifugal washing, and is dispersed in a solvent G, such that a metal-doped titanium oxide quantum dot solution is obtained. The invention relates to broadening of absorption of titanium dioxide quantum dot to visible region, however, it does not relate to stability of quantum dot, and the stability of quantum dot is of great importance to actual application.